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Dissertations / Theses on the topic 'Attachment organs'
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1
Yu, Samuel Shing Chi. "Covalent Attachment of Nanoscale Organic Films to Carbon Surfaces." Thesis, University of Canterbury. Chemistry, 2008. http://hdl.handle.net/10092/4083.
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Modification of planar graphitic carbon surfaces by the attachment of molecular films has been investigated in this work. Molecular layers have been grafted to glassy carbon (GC) and pyrolyzed photoresist film (PPF) by employing a range of techniques, which involved electrochemically and photochemically assisted procedures. Modification methods involve the electrochemical reduction of aryldiazonium salt, electrochemical oxidation of arylcarboxylate and photolysis of alkene, alkyne and azide on carbon surfaces. For these methods, it is proposed that reactive species are generated by the procedures, which leads to the grafting of modifiers to the carbon surfaces. A selection of molecular species was grafted to GC and PPF by these method containing different terminal R-functional groups that include —COOH, -NO₂, -NH₂, and —NCS. The grafted R-functional groups permit for further chemical reactions on the surface. Electrochemically and photochemically grafted films were examined with a combination of water contact angle measurements, cyclic voltammetry, X-ray electron spectroscopy XPS, optical microscopy, scanning electron microscopy SEM and atomic force microscopy AFM. Film properties such as surface concentration, film thickness, wettability, chemical composition and reactivity were characterized by the above mentioned techniques. Films electrochemically prepared from aryldiazonium salts and arylcarboxylates, under the conditions applied in this work, formed loosely packed multilayers with typical film thicknesses of les than 5 nm. Photochemically grafted films prepared from alkenes and azides, in general, formed loosely packed monolayers with film thicknesses of less than 2 nm. Loosely packed multilayers were also prepared from alkene and alkyne by photochemical procedures. ii Chemical reactions on grafted films were demonstrated and analyzed by a combination of the above mentioned characterization techniques. In particular, the reduction of nitrophenyl (NP)films, amine-coupling reactions, photoactivation of grafted films with oxalyl chloride and electrostatic assembly of anionic gold nanoparticles were investigated. Selected chemical reactions permitted identification and evaluation of the grafted layers, and demonstrated the ability to control the immobilization of chemical species. Microscale chemical patterning of two different types of modifiers on carbon surfaces was demonstrated using photolithographical techniques that utilized photochemical reactions with azides. Patterns of line-arrays with line widths of hundreds of micrometers to 10 µm were formed.
2
Crowe, Loretta L. "Reversible Attachment of Organic Dyes to Silica Surface Through Meijer-Type Hydrogen Bonding." Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14058.
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In an approach to creating molecular-scale structures on glass surfaces via self assembly, a strongly-dimerizing ureido-[2-(4-pyrimidone)] (UPy) quadruple hydrogen-bonding array was chemically immobilized on silica surfaces by way of a triethoxysilane functionality. The unreacted surface silanols were then thoroughly passivated with a monofunctional organosilane, resulting in isolated UPy binding sites on the glass surface. These binding sites were found to selectively bind the strongly fluorescent perylenediimide (PDI) functionalized UPy molecules from solution, thus non-covalently linking the fluorophore to the surface. The association between the self-complementary molecules was exceptionally strong, both in solution and at the surface, such that effective hydrogen-bonding was retained after most solvent treatments. The binding was also reversible, however, so that washes with polar protic and dipolar aprotic solvents with high hydrogen-bonding capabilities, such as water, alcohols, and DMSO, resulted in the removal of the non-covalently bound fluorophore-tagged UPy.
The UPy:UPy dimer system was also investigated in solution, using pyrene intramolecular excimer formation as a monitor of the dissociation of the pyrene heterodimers into homodimers incapable of forming excimers at micromolar concentrations. In addition, the energy transfer process in solution between pyrene and perylenediimide fluorophores linked through UPy dimerization was studied, with the intention using FRET-based measurements on the surface at single-molecule levels in order to determine the distances between UPy binding sites. Energy transfer was found to occur, but the observed photophysical behavior was complicated by possible secondary processes, which steady-state fluorescence measurements were unable to elucidate.
The benefit of using this UPy system for attaching molecules to a surface lies in its reversibility of binding and versatility in manner of molecules which van be retained on the modified surface with a strong association. In this way molecular-scale features could conceivably be constructed on a surface by self-assembly, with the option of further chemical reactions to lock them in place, thus creating structures beyond the accessibility range of the conventional lithographic methods.
3
Skolimowska, Ewelina Szymanska. "Dissociative electron attachment and dipolar dissociation processes in organic molecules found in the interstellar medium." Thesis, Open University, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.606955.
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In this thesis, the results of a series of experimental studies of electron induced anion formation are presented for a number of molecular targets. The motivation of this work was the discovery of anions in interstellar space and in planetary atmospheres raising the question of how such species are formed. Molecular anions are commonly formed by electron impact via the Dissociative Electron Attachment (DEA) and Dipolar Dissociation (DD) with the simultaneous formation of neutral often reactive species (in case of DEA) and cationic fragments (in case of DD). These fragments may then undergo reactions leading to the chemical synthesis of larger stable products. Thus electron induced chemistry may provide a hitherto unexplored route of molecular synthesis and aid in our understanding of the role of anions in interstellar and atmospheric chemistry. .
4
Woods, Timothy E. "Elucidating the degree of selectivity for NLO surrogate attachment to model compounds and a co-polyimide using the Mitsunobu reaction /." Online version of thesis, 2008. http://hdl.handle.net/1850/7725.
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5
Zhang, Fangmei. "DISTRIBUTION OF METABOLIC CHARACTERISTICS AMONG AEROBIC SOIL BACTERIA AND IMPLICATIONS FOR BIOTRANSFORMATION OF ORGANIC AND METALLIC WASTES." Case Western Reserve University School of Graduate Studies / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=case1164998429.
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6
Rizzo, Francesco. "Computational characterization of carbazole-benzonitrile derivatives for applications in Organic Light Emitting Diodes." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/21022/.
Full textAbstract:
The technology of Organic Light-Emitting Diodes has reached such a high level of reliability that it can be used in various applications. The required light emission efficiency can be achieved by transforming the triplet excitons into singlet states through Reverse InterSystem Crossing (RISC), which is the main process of a general mechanism called thermally activated delayed fluorescence (TADF). In this thesis, we theoretically analyzed two carbazole-benzonitrile (donor-acceptor) derivatives, 2,5-di(9H-carbazol-9-yl)benzonitrile (p-2CzBN) and 2,3,4,5,6-penta(9H-carbazol-9-yl)benzonitrile (5CzBN), and addressed the problem of how donor-acceptor (D-A) or donor-acceptor-donor (D-A-D) flexible molecular architectures influence the nature of the excited states and the emission intensity. Furthermore, we analyzed the RISC rates as a function of the conformation of the carbazole lateral groups, considering the first electronic states, S0, S1, T1 and T2, involved in TADF process. The two prototype molecules, p-2CzBN and 5CzBN, have a similar energy gap between the first singlet and triplet states (∆EST, a key parameter in the RISC rate), but different TADF performances. Therefore, other parameters must be considered to explain their different behavior. The oscillator strength of p-2CzBN, never tested as emitter in OLEDs, is similar to that of 5CzBN, which is an active TADF molecule. We also note that the presence of a second T2 triplet state, lower in energy than S1 only in 5CzBN, and the reorganization energies, associated with RISC processes involving T1 and T2, are important factors in differentiating the rates in p-2CzBN and 5CzBN. For p-2CzBN, the RISC rate from T2 to S1 is surprisingly higher than that from T1 to S1, in disagreement with El-Sayed rules, due to a large reorganization energy associated to the T1 to S1, process; while the contrary occurs for 5CzBN. These insights are important for designing new TADF emitters based on the benzo-carbazole architecture.
7
Dang, Thao P. "Biomimetic Modeling of the Nitrogen-centered Radical Postulated to occur during the Inhibition of Ribonucleotide Reductases by 2'-Azido-2'-deoxynucleotides." FIU Digital Commons, 2010. http://digitalcommons.fiu.edu/etd/318.
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Ribonucleotide reductases (RNR) are essential enzymes that catalyze the reduction of ribonucleotides to 2'-deoxyribonucleotides, which is a critical step that produces precursors for DNA replication and repair. The inactivation of RNR, logically, would discontinue producing the precursors of the DNA of viral or cancer cells, which then would consequently end the cycle of DNA replication. Among different compounds that were found to be inhibitors of RNR, 2'-azido-2'-deoxynucleotide diphosphates (N3NDPs) have been investigated in depth as potent inhibitors of RNR. Decades of investigation has suggested that the inactivation of RNR by N3NDPs is a result of the formation of a nitrogen-centered radical (N•) that is covalently attached to the nucleotide at C3' and cysteine molecule C225 [3'-C(R-S-N•-C-OH)]. Biomimetic simulation reactions for the generation of the nitrogen-centered radicals similar to the one observed during the inactivation of the RNR by azionuclotides was investigated. The study included several modes: (i) theoretical calculation that showed the feasibility of the ring closure reaction between thiyl radicals and azido group; (ii) synthesis of the model azido nucleosides with a linker attached to C3' or C5' having a thiol or vicinal dithiol functionality; (iii) generation of the thiyl radical under both physiological and radiolysis conditions whose role is important in the initiation on RNR cascades; and (iv) analysis of the nitrogen-centered radical species formed during interaction between the thiyl radical and azido group by electron paramagnetic resonance spectroscopy (EPR). Characterization of the aminyl radical species formed during one electron attachment to the azido group of 2'-azido-2'-deoxyuridine and its stereospecifically labelled 1'-, 2'-, 3'-, 4'- or 5,6-[2H2]-analogues was also examined. This dissertation gave insight toward understanding the mechanism of the formation of the nitrogen-centered radical during the inactivation of RNRs by azidonucleotides as well as the mechanism of action of RNRs that might provide key information necessary for the development of the next generation of antiviral and anticancer drugs.
8
Liong, Rolan Yuk Loong. "BACTERIAL GROWTH ON METAL AND NON-METAL SURFACES IN A STATIC BIOREACTOR." DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/923.
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Research was conducted to observe bacterial growth on the surface of metals in a static bioreactor. Metal and non-metal samples were subjected to bacterial exposure (1 day and 9 days). The metal samples were surface treated prior to bacterial exposure. The microstructures of the surface treated samples were analyzed by optical microscopy. After exposure, the microstructures of the samples were analyzed by scanning electron microscopy (SEM). The analysis suggested that microbial attachment on the surface was related to the underlying microstructure of steel. The preferential attachment of microbes could potentially be influenced by cathodic and anodic regions created by the electrolytic cells.
9
Theunissen, Maxine. "Morphology and functioning of attachment organs of the Polystomatidae (Monogenea) / Maxine Theunissen." Thesis, 2014. http://hdl.handle.net/10394/15953.
Full textAbstract:
Monogeneans are mainly ectoparasitic on fish, but the family Polystomatidae radiated
onto tetrapods and can be found on the skin and gills of the Australian lungfish, in the
urinary bladder of frogs, gills and skin of salamanders, cloaca and phalodeum of
caecileans, on the eye, nostrils, mouth, cloaca or urinary bladder of freshwater turtles,
and on the eye of the hippopotamus. These host organisms are ecologically related
through their association with freshwater habitats that favour parasite transmission. Firm
attachment is critical to maintain a close relationship with their hosts. Attachment organs
usually comprise of several units that are semi related to each other due to the need to
form a functional unit. Interactions between subunits are expected to be under
stabilising selection, and therefore hinder evolutionary change. Monogeneans are
renowned for their effective posterior attachment structures in the form of hooks or
hamuli and suckers that secure them, permanently or semi-permanently, to their hosts.
The aim of this study was to investigate the morphology and functioning of attachment
organs of selected polystomes representing different genera. A number of genera were
selected in the study of attachment structures, genera included: Protopolystoma,
Polystoma, Eupolystoma, Neopolystoma, Polystomoides and Oculotrema. Light
microscopy and scanning electron microscopy was used to study the external
morphology. Histology followed by light microscopy, confocal microscopy and enzyme
digestion techniques followed by scanning electron microscopy was used to study the
internal morphology. It was found that variation in haptoral components do exist, even
among congeners, living for example in the bladder and oral cavity of the same host.
Environmental factors relating to host ecology need to be taken into account when
studying the morphology of monogenean haptors. Such factors play an important role in
the adaptation of monogeneans and have possibly led to the change in microhabitats,
which in turn explain the variation of haptoral components between parasites. Not all
haptoral structures necessarily function in attachment throughout the entire life of the
parasite and different haptoral structures are important for attachment to the host at
different developmental stages of the parasite.PhD, North-West University, Potchefstroom Campus, 2015
10
Lin, Po-Yuan, and 林柏遠. "Study of organic solar cell and organic lightemitting device with microlens array film attachment." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/92077630949233473246.
Full textAbstract:
碩士國立東華大學
材料科學與工程學系
101
This thesis is divided into two parts: Application of microlens array on organic photovoltaic devices and study on organic light-emitting device (OLED) polarized. In the first part of this thesis, we produced an organic photovoltaic device and reflection organic photovoltaic devices with different angles attached to different gap arranged microlens array illuminated observation of the short circuit current density (JSC) changes, and to identify the best efficiency microlens array. Studies in the oblique Illumination through the microlens array into the element of the multiple reflection effect. The reflection organic photovoltaic devices with micro-lens array in normal illumination increases the short circuit current density ( JSC ) by 11 %. The maximum the JSC to enhance 39% in the variable angle to 55 °. The second part of this thesis, we using organic light-emitting device (OLED) based on indium tin oxide (ITO)/ N,N-Bis (naphthalen-1-yl) -N,N-bis (phenyl) benzidine (NPB) (60 nm)/ 8-hydroxyquinoline aluminum (Alq3) (20~140 nm)/ lithium fluoride (LiF) (12 nm)/ aluminum (100 nm). We change the thickness of the element electron transporting layer (ETL) and emitting layer (ETL) (Alq3) is to explore different thickness photovoltaic characteristics. Use of polarizer separation of vertically polarized (VP) and parallel polarized (PP) to see such as spectral shift and the light intensity change.
11
Sheng-Chih, Hsu. "Blur Effect and Light Efficiency Enhancement of Organic Light-Emitting Devices by Using Microstructure Attachment." 2006. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-2607200618125500.
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Lin, Tsung-Yu, and 林宗瑜. "Image Quality and Light Efficiency Enhancement of Organic Light-Emitting Devices by Using Microstructure Attachment." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/82521291541002203369.
Full textAbstract:
碩士國立臺灣大學
光電工程學研究所
95
In this thesis, we set up a simulation model of organic light-emitting devices (OLED) with microstructure attachment. We demonstrated the simulation model and ray tracing analysis with the optical software LightTools TM. In order to improve the out coupling efficiency, we considered the total internal reflection (TIR) between air and substrate interface is a key place to be modified. We apply the micro-pyramid array to organic light-emitting devices (OLED) to reduce the total internal reflection (TIR) between air and substrate interface. Instead of merely concerning the efficiency for lighting purposes, we must take both the light extraction efficiency and image quality into account for display applications. In this simulation, we modulate some parameters such as base width, base angle, fill factor and arrangement of perfect micro-pyramid and truncated micro-pyramid, and try to find out the effects on angular intensity distribution, total power enhancement, and blurred image of the OLED. Finally we bring up several new microstructures and arrangement to control the blur effect and increase light extraction efficiency significantly.
13
Hsu, Sheng-Chih, and 許聖志. "Blur Effect and Light Efficiency Enhancement of Organic Light-Emitting Devices by Using Microstructure Attachment." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/19561787051739967102.
Full textAbstract:
碩士國立臺灣大學
光電工程學研究所
94
In this thesis, we demonstrated the simulation results of optical performance of organic light-emitting devices (OLED) by different kind of microstructure attachment. The simulations include the intensity, luminance efficiency, power efficiency, blurred image, and blur-width of the device which is attached by different microstructures. For lighting applications, we focus on light extraction efficiency and intensity distribution. For display applications, we pay attention to blurred image and blur-width. We also take the power and luminance enhancement into consideration. Finally, we bring up an innovation about specific arrangement of microstructure array on OLED display. We conclude the design rule for some parameters such as size, area ratio, height ratio, and arrangement of microlens array.
14
Chiu, Szu-Jung, and 邱思蓉. "Cold Plasma Deposited Organic Film on Stainless Steel to Improve Corrosion Resistant and Cell Attachment." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/64647640236981505138.
Full textAbstract:
碩士大同大學
材料工程學系(所)
94
Stainless steels were widely used in biomaterials due to their high impact strength, high resistance to wear, ductile, absorption of high strain energy properties. However, the disadvantages of stainless steels were low biocompatibility and will corrosion in physiological environment. Besides, stainless steels are an inorganic and inert materials, will limited its surface drug immobilization and medical application. Chondroitin-6-sulfate (C-6-S) is the bulk of the matrix that builds vertebral discs, ligaments, cartilage and other connective tissues. It was widely distribution in human body, so it’s a biocompatible biomolecular. The easy way of improve biocompatibility of specimens is to immobilize biomolecular on the surface. In this study, the plasma deposition methods were used to obtain insulator and anticorrosion coating, and subsequent to surface graft polymerization of water soluble monomers for immobilized chondroitin-6-sulfhate to improve cell attachment. From FTIR and ESCA, the C-6-S were successful immobilized on specimens. The potential dynamic tests results shown that stainless steel through plasma deposited Hexamethyldisilazane (HMDSZ), the corrosion behavior can be controlled. Future more, the hydrophilic and biocompatibility can be improve after graft polymerization of water soluble monomers acrylic acid and then immobilized chondroitin-6-sulfhate through EDC (carbodiimide) cross linked.
15
Lin, Tsung-Yu. "Image Quality and Light Efficiency Enhancement of Organic Light-Emitting Devices by Using Microstructure Attachment." 2007. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-2407200713442500.
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